In recent years, a number of different methods have been developed for causing conventional optical fibers to emit light. U.S. Letters Pat. Nos. 3,508,589 to B. N. Derick et al and 4,234,907 to M. Daniel disclose methods for causing clad or unclad optical fibers to emit light along the length of the fiber. This may be accomplished by scratching, abrading, chemically deforming, or otherwise removing or disturbing portions of the cladding of the optical fibers so that a small percentage of light traveling down the length of the fibers is emitted through the deformities in the cladding. Similarly, light emission may be achieved by providing optical fibers having a core region which is doped with refractive and/or reflective light scattering particles to provide enhanced, uniform light emission along the length of the optical fiber without the need for fiber deformation as disclosed in U.S. Letters Pat. No. 4,466,697 to M. Daniel.
Panels with surfaces composed of light emitting woven optical fibers have been proposed by the aforementioned Derick et al and Daniel patents, while panels composed of strips of light conducting glass or plastic, such as described in U.S. Pat. No. 4,172,631 to Yevick, have been proposed as a means of producing a light emitting panel. However, panels constructed in accordance with these prior art methods have proven difficult to fabricate, since panels formed with light conducting glass or plastic strips require that each strip be cut with great precision. On the other hand, panels formed from woven light emitting optical fibers have never been developed to emit light uniformly and often have dark or shaded areas which extend across areas of the panel.
The technology dealing with light emitting optical fiber assemblies has, to this point, been directed toward obtaining light emission of any character along the length of a fiber and developing components which might ultimately find use in an assembly incorporating light emitting optical fibers. Thus, light sources have been designed which transmit light from a single point light source over a plurality of paths as shown by U.S. Letters Pat. No. 4,222,091 to C. Bartenbach, and this has led to the transmission of light from a single source to a plurality of light transmitting cables as disclosed in U.S. Letters Pat. Nos. 3,437,804 to V. Schaefer et al and 4,459,642 and 4,459,643 to K. Mori. These light source developments have led to the design of curved light paths emanating from a central hub, as shown by U.S. Letters Pat. No. 3,567,917 to W. Daley, and ultimately to the spiral galaxy mirror light collection assemblies illustrated in U.S. Letters Pat. No. 4,576,436 to M. Daniel.
Other optical components, such as the optical mixer disclosed in U.S. Letters Pat. No. 4,523,257 to K. Mori, have been developed for use in optical systems, but such prior art units are not designed for combination with other optical components in a complete illumination system to maximize the efficiency of the system while providing uniform illumination. In an effective illumination system, focused light from a high intensity light source should be distributed by an effective reflector system onto the input aperture for an optical mixer which will provide a defocused light output. Both the reflector system and the optical mixer will often be required to have a heat dissipation capability, since excess heat will normally be generated by a high intensity light source.
To this point, optical fiber light emitting panels have been primarily experimental, and the requirements for a commercially acceptable panel have not been met. There is a great difference between the theoretical generalization that woven optical fiber might emit light and the production of commercially acceptable light emitting panels which will uniformly emit light from an extensive surface area. The generalization can be supported by small, hand woven patches of fabric formed from optical fibers, but the problems involved in providing light to a plurality of panel sections having a substantial surface area and causing the substantially uniform emission of light from these surface areas remain to be solved.